ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1pPA1. New frontiers in molecular acoustics of liquids.

Armen Sarvazyan

Dept. of Chem., Rutgers Univ., New Brunswick, NJ 08903

The major accomplishments in molecular acoustics of liquid systems are
summarized. The most promising direction in this field is acoustical
thermodynamics. The possibility of acoustical evaluation of thermodynamic
parameters of liquids comes from the fact that compressibility of the fluid is
the second derivative of Gibbs free energy on pressure. Changes of enthalpy,
entropy, free energy, and their pressure and temperature derivatives (heat
capacity, volume, expansibility, compressibility, etc.) can be calculated from
the pressure and temperature dependencies of sound velocity in the fluid by
using additionally the data on the temperature dependencies of density and heat
capacity of the fluid at 1 atm. Another new area is related to the studies of
the acoustic nonlinearity parameter B/A which is a simple function of the
pressure derivative of the bulk modulus and provides unique information on the
character of intermolecular forces in the liquid. In aqueous solutions B/A is
significantly determined by the structure of water in the hydration shell of
the solute. The state of the art in the instrumentation for molecular acoustic
studies is presented. New types of acoustical resonators based on the use of
cylindrical standing waves enabling one to make measurements in microliter
volume samples will be described. [sup a)]Permanent address: Institute of
Theoretical and Experimental Biophysics, Russian Academy of Sciences.